I have before and after buttons on a hidden page along with 400 buttons - each one for one slot in the changer. The number buttons have links to have actions that are something like

Link to Before
Link to 3
Link to 3
Link to 1
Link to After.

This takes you to disc 331.

The before button contains several actions like stop, display, right cursor.
and after contains similar actions. Basically, whatever needs to be entered before the number is on the before button and everything that needs to be entered after the number is on the after button.

The advantage of this is that if you need to make a change to your macros you only need to make it in one place. The DVD image simply links to the number macro. Hope this makes sense.